Avalanche Advisory

Turnagain Area Avalanche Advisory

Tuesday, December 31st 2013 6:39 am by Wendy Wagner

ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.

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The Bottom Line

There remains aMODERATEavalanche danger for triggering either a slab avalanche 12-18” deep or a fresh wind slab ~6" deep. Areas most concerning are steep slopes (approaching 40 degrees and steeper) and all aspects near and above treeline. Below treeline the danger is LOW where the snow cover is mostly loose unconsolidated snow.

*Avalanche danger will rise tonight into tomorrow as a strong storm system is bringing in the New Year.

Show the Complete North American Avalanche Danger Scale

North American Public Avalanche Danger Scale

Avalanche danger is determined by the likelihood, size and distribution of avalanches.

Danger Level

Travel Advice

Likelihood of Avalanches

Avalanche Size and Distribution

5 Extreme

Avoid all avalanche terrain.

Natural and human- triggered avalanches certain.

Large to very large avalanches in many areas.

4 High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human- triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

The weak snow that is buried 12-18” deep in our snowpack remains our primary concern. The likelihood for triggering a slab avalanche that breaks in this older weak snow has been decreasing the last several days but the possibility does remain.

We have a small shot of snow expected today (1-3” forecast) with moderate to strong wind. Slopes where the wind is depositing snow will add stress to these buried weak layers and increase the likelihood of triggering one of these old slabs. However, the ‘real’ snow and wind event is expected overnight tonight through tomorrow where a foot or more of new snow will have the potential to overload the weak layers. We could see large and unmanageable avalanches 2-3+' deep by tomorrow if this storm does verify.

Below treeline the slab is losing its cohesion and the pack is unsupportable. Though there is some localized collapsing in the alders, triggering an avalanche is unlikely.

Avalanche Problem 2

Easterly winds will start picking up through the day to the moderate range on the ridgelines with gale force winds expected for tonight. Though there is limited snow to transport at the moment, we do have 1-3” of snow forecast to fall before 6pm. Watch for wind drifts and shallow slabs to start forming through the day. These should be confined to above treeline slopes and exposed rollovers.

Mountain Weather

We have had a mild past 24-hours with temperatures in the mid 20’s F above sea level, light easterly winds at ridge tops and overcast skies.

Today a change is in store as a large area of low pressure heads our way from the South. We should see East winds pick up by the afternoon to the 30-40mph range on the ridgelines with 70-80mph by late tonight. Temperatures should be around 20F above treeline and near 32 at sea level. Snow accumulation of 1-3” is expected with a snow/rain mix at sea level.

By tomorrow evening we are looking a total snowfall of 12-16” (possibly more). The models are saying around 1.5” of water equivalent from this afternoon through Wednesday night. It does look like we could finally get a decent shot of snow.

Some December stats below:

We end 2013 with a SWE that is only 15% of average for December. We also made the podium with this December being the 3rd driest since 1983. Numbers below are from the Turnagain Pass SNOTEL Station (1880’).

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Dec 18, 2018 )

AREA

STATUS

WEATHER AND RIDING CONDITIONS

Glacier District

Johnson Pass:

Open

Please stay on trail to avoid resource damage through Forested areas.

Placer River:

Closed

Closed

Skookum Drainage:

Closed

Closed

Turnagain Pass:

Closed

Closed November 21 due to inadequate snow conditions. #hopeforsnow

Twentymile:

Closed

Closed

Seward District

Carter Lake:

Open

Lost Lake Trail:

Open

Please stay on trail to avoid resource damage through Forested areas.

Primrose Trail:

Open

Please stay on trail to avoid resource damage through Forested areas.

Resurrection Pass Trail:

Closed

Closed for the 2018/19 season. Next season will be open to motorized use.

The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur.
This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.